Device useful in the treatment of blood

ABSTRACT

Device useful as a heat exchanger for blood or as an apparatus in which blood may be treated or reacted with selected reactants. Device comprises hollow tubing which has spacing means on its outer surface, said spacing means being in the form of continuous or discontinuous projections or ridges of material. Hollow tubing having such spacing means is also included.

This is a division of application Ser. No. 021,373, filed Mar. 19, 1979,now abandoned.

FIELD OF THE INVENTION

This invention relates to devices useful in the treatment of blood orsimilar biological fluids. More particularly, this invention relates toa device which can serve as a heat exchanger for blood or which can beused as a reactor in which blood is reacted with selected reactants orwhich can serve both of these purposes simultaneously.

BACKGROUND OF THE INVENTION

Current medical treatment frequently involves the extracorporealtreatment of blood, that is, blood is removed from a patient's body,treated, and then returned to the patient. Thus, for example, during thecourse of open heart surgery, blood is removed from a patient,oxygenated in a suitable oxygenating device, and returned to thepatient. In the case of kidney malfunction or failure, blood is removedand treated, for example, in a dialyzer to remove toxic metabolites. Thepurified blood is then returned to the patient.

In the above or other instances, it may be necessary or desirable to addcertain additives to the blood. For example, where blood is beingdialyzed or oxygenated, heparin or a similar anticoagulant may be addedto the blood after it has been withdrawn from the patient and before itis dialyzed or oxygenated.

In still other instances, it may be desirable to add reactants to theblood after it has been taken from a patient in order to achieve adesired medical effect. For example, it has been proposed to treatsickle cell anemia by a process which includes reacting a patient'sblood with cyanate ion in a suitable extracorporeal device. See Vol. XX,Transactions of the American Society of Artificial Internal Organs, page574 (1974).

In extracorporeal treatments, such as those mentioned above, thetemperature of the blood taken from the patients corresponds to thepatient's body temperature which, in normal circumstances, is about98.6° F. The extracorporeal environment to which the removed blood isexposed has a temperature which is considerably lower, usually about 68°F. to 72° F. Heat exchangers may be employed in such instances in orderto insure that blood returned to the patient has the desiredtemperature. Heat exchangers are also employed in extracorporeal bloodcircuits where it is desired to either raise or lower the temperature ofthe blood after it has been withdrawn from the patient and prior to itstreatment or reaction thereof.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a deviceuseful in the extracorporeal treatment of blood. The device comprises acasing having a hollow interior, a first inlet means, a first outletmeans, a second inlet means, and a second outlet means, a perforatedhollow core secured within said casing, the interior of said core beingin fluid communication with said first inlet means and a length ofhollow tubing having a first end and a second end, the first end of thetubing being connected to said second inlet means and the second end ofsaid tubing being connected to said second outlet, said tubing havingspacing means on the outer surface thereof, said tubing being coiledaround the outside of said core and within said casing.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more clearly understood with reference to thefollowing detailed description and with reference to the appendeddrawings in which:

FIG. 1 is a view, with some parts in cross-section and other partsbroken away, of a device in accordance with the present invention;

FIG. 2 is a fragmentary view of one kind of tubing which can be used inthe device of FIG. 1;

FIG. 3 is a fragmentary view of another kind of tubing which can be usedin the device of FIG. 1;

FIG. 4 is a fragmentary view showing how two portions of the tubing ofFIG. 2 are arranged with respect to one another in the device.

FIG. 5 is a view of a fluid spreading means which may be used in thedevice of FIG. 1; and

FIGS. 6 and 7 are detail views of a portion of the device of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to FIG. 1 of the appended drawings, there is shown device10 in accordance with the present invention. Device 10 comprises anelongated, cylindrical hollow casing 12, an elongated, cylindricalperforated hollow core 22 generally centrally located within casing 12,and hollow tubing 32 wrapped in coil form around core 22.

Hollow casing 12 is formed from two open-ended cylinders 12a, 12b. Eachsuch cylinder comprises a closed end portion and a cylindrical wallportion and each has a small flange, 11a and 11b respectively, at itsopen end. The two cylinders are joined at their flanges by ultrasonicwelding or with a suitable adhesive to give a leakproof seal. Theresulting hollow casing 12 comprises a first or top end portion 13, asecond or bottom end portion 14, and a generally cylindrical side wall15. The hollow casing has a first inlet means 16 in the bottom thereofand a first outlet means 17 in the top thereof. In addition, casing 12has a second inlet means 18 and a second outlet means 19 which, in thepreferred embodiment, are located in top end 13. The various outlets areconnected in fluid tight relationship to casing 12. Preferably, thecasing and outlets are made from polystyrene; other materials ofconstruction, such as polycarbonate, may be substituted.

In the preferred embodiment, hollow core 22 is substantially smaller indiameter than casing 12 and has a series of square shaped apertures 24.These apertures are substantially uniform in size, each measuring about0.2 inch by 0.2 inch and having an area of about 0.04 inch². Apertures24 occupy about 50% of the surface area of the outer cylindrical wall ofcore 22. Other aperture shapes such as rectangular, circular, oval,diamond, triangular, etc. are also suitable.

Hollow core 22 further comprises a top flange 24 and a bottom flange 25,each of which is circular and sized so as to fit within casing 12.Flange 25 has an opening 27 therein which is in fluid communication withthe interior of core 22 and the interior of inlet 16. Flanges 24, 25 aresealed to the ends of the core with, for example, an epoxy resinadhesive.

A gasket in the form of O-ring 28 is placed between the bottom surfaceof flange 25 and the inner surface of bottom end 14 of the casing toform a fluid tight seal. The O-ring, which has a diameter somewhatlarger than the diameter of opening 27 in flange 25, can be made fromsilicone rubber or the like. Alternatively, adhesive may be substitutedfor the O-ring, such adhesive serving not only as a gasketing materialbut also as means for securing core 22 within casing 12. Flange 24 isgenerally circular and has openings 24a and 24b therein. There is asubstantially uniform clearance of about 0.06 inch between the peripheryof flange 24 and the inside surface of cylindrical wall 15. As will beseen, this clearance, along with openings 24a, 24b, provides a path forfluid to reach first outlet 17 at the top of the device.

Referring now to FIGS. 2-4 of the drawings, hollow tubing 32 comprisesordinary tubing 33 having spacing means 34 on its outer surface. Thesespacing means minimize the degree of contact between adjacent sectionsor portions of tubing when it is wrapped around core 22 and to provideopenings 35 for passage of a fluid such as a heat exchange medium. Thespacing means comprise a ridge or projection of material placed in awinding pattern on the outer surface of tubing 33. This ridge orprojection of material may be either continuous or discontinuous. Asseen in FIG. 2, the spacing means 34 comprise a continuous length ofmonofilament which is wrapped in a generally spiral fashion around theouter surface of a length of ordinary tubing 33. Monofilament 34preferably comprises nylon having an outside diameter of 0.029 inch.Strands of wire such as stainless steel or monofilament of other commonplastic materials may be substituted for the nylon monofilament. Tubing33 must have sufficient flexibility to be formed into a coiledconfiguration and enough strength to withstand the pressure of fluidsflowing therethrough. Tubing 33 is preferably made of polyvinylchloride, but other material such as stainless steel, polyethylene orsilicone rubber could also be used. Tubing 33 having an inside diameterof about 0.2 inch and an outside diameter of about 0.27 inch has beenfound suitable for use in device 10. Tubings having various dimensionsmay be employed; however, the inside diameter of the tubing should notbe less than about 0.01 inch nor greater than about 1 inch.

Referring to FIG. 2, the angle θ at which the longitudinal axis of themonofilament intersects the longitudinal axis of tubing 33 may rangefrom about 10° to about 80°. It is preferable, however, that this anglerange from about 20° to 70° and even more preferably, the angle θ shouldrange from about 35° to about 65°. Although tubing comprising a singlelength of monofilament may be used, it is preferred, as illustrated inFIG. 3, that tubing 32 comprise two lengths of monofilament, 34a, 34b,wrapped around tubing 33, the monofilaments being wrapped in oppositedirections to give two continuous ridges of material having crossoverpoints 37.

As a non-limitative illustration, it has been found that a satisfactoryembodiment of tubing 32 can be made by spirally wrapping tubing 33having an outside diameter of about 0.27 inch with two individualmonofilaments of nylon having an outside diameter of about 0.029, sothat angle θ between the longitudinal axis of either of themonofilaments and the longitudinal axis of the tubing is about 49°. Theadditional advantage (aside from its spacing function) to be derivedfrom tubing 32 illustrated in FIG. 3 are twofold. First, the twomonofilaments are frictionally engaged at their crossover points 37 andthis helps prevent slippage of the monofilaments which might otherwiseoccur. Second, the crossover points 37 provide a "double thickness" ofspacing material.

Variations of the structure shown in FIG. 3 will be obvious to thoseskilled in the art. Additional lengths of monofilament, e.g., three ormore could be employed. Additionally, two monofilaments could be woundaround tubing 33 in the same direction in spaced apart relationship. Thelatter mentioned structure does not have the additional advantagesmentioned in the foregoing paragraph, but is nonetheless suitable foruse in the invention. Where two or more monofilaments are used, theirrespective axes may make different angles θ with the longitudinal axisof the tubing 33. It will be apparent that the spacing, d, betweenadjacent crossover points 37 will be a function of the outside diameterof tubing 33 and the angle(s) at which the monofilaments are wrappedtherearound.

The spacing means comprising the projections or ridges of material onthe outer surface of the tubing can be formed by means other thanwrapping with a length of plastic monofilament. For example, stainlesssteel or similar wire or other kinds of plastic may be substituted forthe aforementioned nylon monofilament. Alternatively, the projections orridges on the outer surface of the tubing can be provided during themanufacturing operation by extruding a base material, e.g., polyvinylchloride, through a die whose configuration corresponds to theconfiguration desired for the tubing. In addition, projections 34 neednot take the continuous form such as that obtained by wrapping with alength of monofilament material, but may be discontinuous. For example,the desired projections may comprise a plurality of discrete individualpeaks of material arranged on the outer surface of the tubing. Suchindividual peaks of material may be provided in the form of e.g., cones,cones with truncated tops, pyramids, spheres, etc. The important thingis that there be at least one course of projections or ridges ofmaterial around the tubing.

As can be seen in FIG. 1, tubing 32 is wound around core 22 in spiralfashion to provide four layers 38a, 38b, 38c, 38d of turns lyingoutwardly in the radial direction from core 22 toward the inner wall ofcasing 12. A fewer or greater number of layers may be employed dependingupon such factors as the size of the casing, the size of the tubing, thedesired hold-up volume, etc. End portions 32a, 32b of tubing 32 areconveniently arranged in device 10 to extend through openings 24a and24b, respectively, in flange 24. End portion 32a of tubing 32 is securedin fluid tight relationship to second inlet means 18, while end portion32b of the tubing is secured in fluid tight relationship to secondoutlet means 19. Openings 24a and 24b are desirably larger than tubing32 so that the aforementioned paths for the flow of liquid will bemaintained. In operation of device 10, fluid may enter end portion 32a,flow through coiled tubing 32, and exit therefrom at end portion 32b.

Where core 22 has not been otherwise secured within casing 12, forexample, by applying a suitable adhesive between flange 25 and bottomend 14 of the casing, it is desirable to insert a spacer element betweenflange 24 and top end 13 of the casing. The spacer element must be suchthat fluid may flow, as indicated by the directional arrows at the leftside of FIG. 1, in unimpeded fashion upwardly in the space between theoutermost layer of tubing 32 and cylindrical wall 15, over the uppersurface of flange 24, and out of the device through first outlet means17. As illustrated in FIG. 6, the spacer element may comprise threesmall pieces 60a, 60b, 60c of solid plastic material placed betweenflange 24 and end wall 13, the pieces being arranged in a spaced-aparttriangular relationship with respect to one another. These pieces ofplastic are sized so that when they are in place, they urge core 22against, and cause compression of, compressible O-ring 28. Core 22 isthus secured within casing 12. Simultaneously, O-ring 28 is brought intoengagement with the bottom surface of flange 25 and the inner surface ofbottom wall 24, thus allowing fluid to flow directly through inlet 16into the interior of core 22 and preventing undesirable radial flow offluid between flange 25 and the bottom wall 14 of the casing.

Another spacer arrangement is shown in FIG. 7. Flange 24 comprises aseries of notches 68 cut into its outer periphery. The spacer elementcomprises a circular spacer ring 65 having a series of holes 66 therein.When assembling the device, spacer ring 65 is placed between flange 24and top end 13, and holes 65 in the spacer are aligned with notches 68in the flange to provide flow paths designated by the arrows in FIG. 7.When flow paths are provided by the arrangement shown in FIG. 7, it isnot necessary to have a clearance between the outer periphery of flange24 and the inner wall of the casing. Thus, it is possible in thisinstance for the diameter of flange 24 to be substantially the same asthe inside diameter of casing 12. Those skilled in the art willrecognize that the presence of flange 24 on core 22 is not critical tothe invention. Device 10 will function as desired even if core 22 doesnot comprise flange 24.

FIG. 5 illustrates a fluid spreading means 50 which can be inserted intothe interior of core 22 to achieve a more uniform distribution of thefluid flowing through the core. The fluid spreading means 50 comprisesan elongated strip of metal or plastic, e.g., polycarbonate, twistedaround its longitudinal axis. Suitably, each three inch section of theelongated strip has a full 360° twist. The twisted strip can be sized sothat it fits snugly within core 22.

Device 10 may be used as a heat exchanger for blood as follows: A sourceof blood, for example, that from a patient, is connected to end portion32a of tubing 32. End portion 32b is connected to tubing which returnsthe blood to the patient. A source of heat exchange fluid, e.g., water,heated to the desired temperature is pumped to inlet 16 of the device.The heat exchange fluid flows into the interior of core 22 and risestoward the top thereof. At the same time, the heat exchange fluid flowsradially through the apertures in the core wall and contacts the outersurface of tubing 32, thus transferring heat to the blood. The heatexchange fluid flows through the spaces 35 between the turns and layersof tubing 32. The arrows designated A and B in FIG. 1 illustrate typicalpaths taken by the heat exchange fluid when the device is in operation.The heat exchange fluid, after flowing radially through the turns andlayers of tubing, flows upwardly in the space between the outermostlayer of tubing 32 and the wall of the casing. The fluid then flowsthrough the space between the casing wall and the periphery of theflange. Additionally, or alternatively, the heat exchange fluid can flowthrough openings 24a, 24b in flange 24. Once the fluid reaches the uppersurface of flange 24 it flows out of device 10 by way of outlet 17 andis returned to the pump for recirculation.

The device may simultaneously be used as a heat exchanger and as anapparatus wherein blood is mixed and/or reacted with other materials.Heparin, for example, may be introduced via a suitable inlet port (notshown) upstream of blood inlet 32a. Mixing of the blood and heparin willbe effected in the coiled portions of tubing 32. As another example, adesired quantity of a solution of potassium cyanate may be addedupstream of the blood inlet. Reaction of the hemoglobin in the bloodwith the cyanate ion occurs in the spiral portion of tubing 32, the rateand extend of the reaction being influenced by, among other factors, thetemperature to which the blood is heated while circulating within tubing32 and the hold-up volume defined by that tubing.

It will be recognized that the blood hold-up volume will be defined byboth the internal diameter of tubing 32 and the total length of tubingused and that the blood hold-up volume may be selected to suit variouscircumstances.

As an alternative structure, it is possible to size flange 24 so thatits diameter corresponds substantially to the inside diameter of casing12. In such event, openings 24a, 24b would provide flow paths by whichthe fluid flowing in casing 12 can reach outlet 17. Additional openings,corresponding generally to openings 24a, 24b, may be provided ifnecessary. Alternatively or additionally, notches may be cut into theperiphery of flange 24 to provide paths for fluid flow. Thus, it will beappreciated that flange 24, either because it has a diameter which issmaller than the inside diameter of casing 12, or because it comprisesthe aforementioned openings such as 24a, 24b, or because it comprisesnotches cut into its periphery, defines at least in part the flow pathby which fluid flowing in casing 12 reaches first outlet means 17.

It will also be understood that, while perhaps less desirable, it ispossible to run the heat exchange fluid through tubing 32 and to run theblood or like material to be heated over the outer surfaces of thattubing. In addition, it is possible to have the heat exchange fluid flowenter the device through "outlet" 17 and exit the device through "inlet"16. Finally, it will be understood that all materials which will becontacted by blood must be non-toxic and non-thrombogenic.

We claim:
 1. A device useful in the treatment of blood, said devicecomprising:(a) a casing having a hollow interior, a top end, a bottomend, a side wall having an inner surface, a first inlet means, a firstoutlet means, a second inlet means, and a second outlet means, (b) acore comprising an upstanding side wall having an outer surface, saidcore being located within said casing and defining means for permittinga fluid flowing into said casing through said first inlet means to flowout of said casing through said first outlet means, (c) a length ofnon-semipermeable tubing having a first end and a second end, the firstend of the tubing being connected to said second inlet means and thesecond end of the tubing being connected to said second outlet means,said tubing having spacing means on the outer surface thereof, theportion of said tubing intermediate its first and second ends beingwrapped generally circumferentially around the outer surface of the sidewall of said core for substantially the entire length of said core toprovide at least one layer of coiled tubing within said casing, and (d)means for permitting said fluid flowing into said casing through saidfirst inlet to contact the outer surface of said at least one layer ofcoiled tubing.
 2. A device according to claim 1 wherein said core ishollow and has a series of apertures in its side wall.
 3. A deviceaccording to claim 2 wherein said apertures occupy about fifty percentof the outer surface area of said side wall.
 4. A device according toclaim 3 wherein said apertures are square.
 5. A device according toclaim 1 wherein said core has a hollow interior.
 6. A device accordingto claim 5 wherein said core includes a bottom flange having an openingtherein which permits fluid communiction between the first inlet meansand the hollow interior of said core.
 7. A device according to claim 6further comprising an annular gasket which surrounds the first inletmeans and the opening in the bottom flange, said annular gasket beingdisposed in fluid tight relationship between said bottom flange and theinner surface of the bottom end of the casing.
 8. A device according toclaim 7 wherein said annular gasket is formed from an adhesive materialwhich also serves to secure said core within said casing.
 9. A deviceaccording to claim 7 wherein said means for permitting said fluidflowing into said casing through said first inlet to contact the outersurface of said at least one layer of coiled tubing comprises a seriesof apertures in said core.
 10. A device according to claim 9 whereinsaid core further includes a top flange which is spaced from the innersurface of the top end of the casing and whose peripheral edge is spacedfrom the inner surface of the side wall of the casing.
 11. A deviceaccording to claim 10 wherein said top flange has two openings locatedinwardly of its peripheral edge.
 12. A device according to claim 11 inwhich the first end of said tubing passes through one of said openingsin the top flange and the second end of said tubing passes through thesecond of said openings in the top flange.
 13. A device according toclaim 9 wherein said core further includes a top flange having at leastone opening located inwardly of its peripheral edge.
 14. A deviceaccording to claim 9 wherein said core further includes a top flangehaving at least two openings located inwardly of its peripheral edge.15. A device according to claim 5 wherein said core comprises a bottomflange and a top flange, said bottom flange having an opening thereinwhich permits fluid communication between said first inlet means and thehollow interior of said core, said top flange having a peripheral edgeand being spaced from the inner surface of the top end of the casing,said device further including an annular gasket which surrounds thefirst inlet means and the opening in said bottom flange and a spacerelement located between said top flange and the inner surface of the topend of the casing, said spacer element being adapted to cooperate withthe top flange of the core and the top end of the casing to urge saidbottom flange, said annular gasket, and the inner surface of the bottomend of the casing into fluidtight engagement, whereby fluid enteringsaid first inlet is directed to the interior of said core.
 16. A deviceaccording to claim 15 wherein said core has a series of apertures in itsside wall.
 17. A device according to claim 16 wherein the peripheraledge of said top flange is spaced from the inner surface of the sidewall of the casing.
 18. A device according to claim 16 wherein said topflange has at least one opening located inwardly of its peripheral edge.19. A device according to claim 16 wherein said top flange has at leasttwo openings located inwardly of its peripheral edge, the peripheraledge of said top flange is spaced from the inner surface of the sidewall of the casing, the first end of said tubing passes through one ofsaid at least two openings and the second end of said tubing passesthrough another of said at least two openings.
 20. A device according toclaim 19 wherein said at least two openings are larger than said tubingends which pass through them.
 21. A device according to claim 5 whereinsaid core comprises a top flange which has a peripheral edge and whichis spaced from the inner surface of the top end of the casing, said topflange having a series of notches cut into its periphery, said devicefurther including a spacer element located between said top flange andthe inner surface of the top end of the casing, said spacer elementcomprising a circular spacer ring having a series of holes therein, theholes in said spacer ring being aligned with the notches in said topflange.
 22. A device according to claim 21 wherein said core furthercomprises a bottom flange having an opening therein which permits fluidcommunication between said first inlet means and the hollow interior ofsaid core, said device further including an annular gasket whchsurrounds the first inlet means and the opening in said bottom flange,said spacer ring being adapted to cooperate with the top flange of thecore and the top end of the casing to urge said bottom flange, saidannular gasket, and the inner surface of the bottom end of the casinginto fluid-tight engagement, whereby fluid entering said first inlet isdirected to the interior of said core.
 23. A device according to claim22 wherein said core has a series of apertures in its side wall and theouter dimension of said top flange is substantially the same as theinside dimension of said casing.
 24. A device according to claim 1wherein there are a plurality of layers of coiled tubing within saidcasing.
 25. A device according to claim 1 wherein said spacing meanscomprises a first continuous length of monofilament which is generallyspirally wrapped around said tubing.
 26. A device according to claim 25further comprising a second continuous length of monofilament which isgenerally spirally wrapped around said tubing.
 27. A device according toclaim 26 wherein said first and second continuous lengths ofmonofilament are wrapped in opposite directions whereby the longitudinalaxis of said first monofilament forms an angle with the longitudinalaxis of said second monofilament at the points of intersection of saidmonofilaments.
 28. A device according to claim 27 wherein said angle isabout 49°.
 29. A core assembly for a reactor suitable for extracorporealtreatment of blood, and comprising:a conduit defining within itself apassage of generally circular cross section for conducting an introducedfluid in a generally first in-first out flow sequence, said conduitbeing wound about a longitudinal axis in a plurality of concentrichelices generating a centrifugally-induced, transverse double torodialsecondary fluid flow within said passage to effect radial mass transporttherewithin and mixing between the center and the periphery of saidpassage; and spacer means at least radially separating adjacent helicesfor permitting circulation of a heat transfer fluid around said conduitin each helix; said spacer means including a ridge member extending in aspiral locus about said conduit.
 30. The assembly in accordance withclaim 29 in which said spacer means also includes means axiallyseparating adjacent turns of said conduit in each said helix.
 31. Theassembly in accordance with claim 29 in which said conduit is tubularand has a wall with an annular cross-section.
 32. The assembly inaccordance with claim 29 in which said ridge member is a generallycylindrical filament wound around the exterior of said conduit.
 33. Alinear reactor for effecting first in-first out, in-line flow sequencefor a first fluid stream and for effecting a thermal energy exchangebetween said first fluid stream and a second fluid stream to attain andmaintain a predetermined first fluid temperature, such as in theextracorporeal treatment of blood, said reactor comprising:a tank meansfor circulating said second fluid and having an inlet for said secondfluid and an outlet for said second fluid; a convoluted conduit definingwithin itself a passage having a generally circular cross section, forconducting said first fluid in a generally first in-first out flowsequence, said conduit having inlet and outlet portions passing throughsaid tank for accommodating the flow of said first fluid, said conduitbeing arranged in a plurality of helices generally concentric about alongitudinal axis and generating a centrifugally-induced, transversedouble toroidal secondary flow within said passage; spacer means atleast radially separating adjacent helices for permitting circulation ofsaid second fluid around said conduit in each said helix to promote heattransfer between said first and second fluids; and a baffle meansdisposed interior of said conduit helices for deflecting a portion ofsaid second fluid flow entering said shell through said inlet away fromsaid longitudinal axis and through said conduit helices.